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Lieselot De Smet, Gertjan Vancoillie, Peter Minshall, Kathleen Lava, Iline Steyaert, Ella Schoolaert, Elke Van De Walle, Peter Dubruel, Karen De Clerck, Richard Hoogenboom
Here, we introduce a novel concept for the fabrication of colored materials with significantly reduced dye leaching through covalent immobilization of the desired dye using plasma-generated surface radicals. This plasma dye coating (PDC) procedure immobilizes a pre-adsorbed layer of a dye functionalized with a radical sensitive group on the surface through radical addition caused by a short plasma treatment. The non-specific nature of the plasma-generated surface radicals allows for a wide variety of dyes including azobenzenes and sulfonphthaleins, functionalized with radical sensitive groups to avoid significant dye degradation, to be combined with various materials including PP, PE, PA6, cellulose, and PTFE...
March 16, 2018: Nature Communications
Hyunjung Oh, Sangil Han, Ashok Kumar Pandey, Sang Hoon Han, Neeraj Kumar Mishra, Saegun Kim, Rina Chun, Hyung Sik Kim, Jihye Park, In Su Kim
The rhodium(III)-catalyzed C-H functionalization followed by intramolecular annulation reactions between azobenzenes and sulfoxonium ylides are described. This protocol leads to the efficient formation of 3-acyl (2H)-indazoles with a range of substrate scope. A high level of chemoselectivity and functional group tolerance of this transformation were also observed.
March 16, 2018: Journal of Organic Chemistry
Ganhua Xie, Pei Li, Zhiju Zhao, Zhongpeng Zhu, Xiang-Yu Kong, Zhen Zhang, Kai Xiao, Liping Wen, Lei Jiang
Water wetting behavior in nano-confined environments plays an important role in mass transport and signal trans-mission of organisms. It is valuable and challengeable to investigate how water behaves in such a nanometer-scale with external stimuli, in particular with electric field and light. Unfortunately, the mechanism of hydrophobic reaction inside the nano-spaces is still obscure and lacks of experimental supporting for the current electric-field- or photo-responsive nanochannels which suffer from fragility or monofunctionality...
March 15, 2018: Journal of the American Chemical Society
Kang-Han Kim, Yong-Cheol Jeong
We present one-step method of fabricating hierarchical multiscale grating patterns by using holographic lithography on azobenzene thin films. In this study, we investigate the growth behavior of surface relief gratings in terms of surface morphology change regarding various optical conditions of different fringe visibility, exposure dose and polarization modes of the light interference pattern. The results reveal that different-sized diffractive gratings could be fabricated orthogonally at the same time. We also explain that these orthogonal gratings were developed through the different light-induced deformation mechanism...
March 5, 2018: Optics Express
C Fedele, P A Netti, S Cavalli
The fabrication of biomaterials whose properties are activated or inhibited on demand via light is appealing for fundamental biological studies as well as for the development of new applications in tissue engineering and regenerative medicine. One of the most widely used molecules in light-controlled systems is azobenzene for its ability to isomerise in response to light. In this minireview, the fundamental landmarks towards the application of azobenzene-containing materials as cell culture substrates will be highlighted, foreseeing their massive use as next-generation cell-instructive materials...
March 12, 2018: Biomaterials Science
Tinkara Mastnak, Aleksandra Lobnik, Gerhard J Mohr, Matejka Turel
The synthesis of two new azobenzene dyes, namely CR-528 and CR-555, and their spectral properties in ethanol solution are described. The recognition of sulfur-containing analytes (2-mercaptoethanol (2-ME), sodium hydrosulfide (NaHS)), and biogenic amines (spermine, spermidine, ethanolamine) bestowed significant spectral changes with color changes from pink/purple to pale yellow/orange-yellow. The nitro acceptor group in the dicyanovinyl reactive dye contributes to higher sensitivity and lower detected analyte concentrations...
March 8, 2018: Sensors
Santanu Mondal, Sangram S Parelkar, Mitesh Nagar, Paul R Thompson
Protein Arginine deiminases (PADs) play an important role in the pathogenesis of various diseases, including rheumatoid arthritis, multiple sclerosis, lupus, ulcerative colitis and breast cancer. Therefore, the development of PAD-inhibitors has drawn significant research interest in recent years. Herein, we describe the development of the first photoswitchable PAD-inhibitors. These compounds possess an azobenzene photoswitch to optically control PAD activity. Screening of a series of inhibitors structurally similar to BB-Cl-Amidine afforded compounds 1 and 2 as the most promising candidates for the light-controlled inhibition of PAD2; the cis-isomer of 1 is 10-fold more potent than its trans-isomer, whereas the trans-isomer of 2 is 45-fold more potent than the corresponding cis-isomer...
March 8, 2018: ACS Chemical Biology
Zhengli Hu, Zi-Yuan Li, Yi-Lun Ying, Junji Zhang, Chan Cao, Yi-Tao Long, He Tian
Identification of the configuration for the photoresponsive oligonucleotide plays an important role in the ingenious design of DNA nanomolecules and nanodevices. Due to the limited resolution and sensitivity of present methods, it remains a challenge to determine the accurate configuration of photoresponsive oligonucleotides, much less a precise description of their photo-conversion process. Here, we used an aerolysin (AeL) nanopore-based confined space for real-time determination and quantification of the absolute cis/ trans configuration of each azobenzene-modified oligonucleotide (Azo-ODN) with a single molecule resolution...
March 8, 2018: Analytical Chemistry
Ziwen Dai, Pik Kwan Lo
We have developed a reversible photoswitching platform based on 3D DNA nanotubes by integrating photoisomerizable azobenzene molecules along the edges. This would allow the reversible conformational changes of the nanotubes between linear and bent features and the switchable patterning of gold nanoparticles in response to UV/Vis irradiation. This work provides a new strategy to create reversibly reconfigurable transformative nanomaterials for potential applications in the fields of renewable energy, sensing, nanorobotics and nanomedicine...
March 8, 2018: Nanoscale
Ling Liu, Patrick R Onck
Switchable materials in response to external stimuli serve as building blocks to construct microscale functionalized actuators and sensors. Azobenzene-modified liquid crystal (LC) polymeric networks, that combine liquid crystalline orientational order and elasticity, reversibly undergo conformational changes powered by light. We present a computational framework to describe photo-induced topographical transformations of azobenzene-modified LC glassy polymer coatings. A nonlinear light penetration model is combined with an opto-mechanical constitutive relation to simulate various ordered and corrugated topographical textures resulting from aligned or randomly distributed LC molecule orientations...
March 7, 2018: Soft Matter
Artur Nenov, Rocio Borrego-Varillas, Aurelio Oriana, Lucia Ganzer, Francesco Segatta, Irene Conti, Javier Segarra-Martí, Junko Omachi, Maurizio Dapor, Simone Taioli, Cristian Manzoni, Shaul Mukamel, Giulio Cerullo, Marco Garavelli
We combine sub-20-fs transient absorption spectroscopy with state-of-the-art computations to study the ultrafast photoinduced dynamics of trans-azobenzene (AB). We are able to resolve the lifetime of the ππ* state, whose decay within ca. 50 fs is correlated to the build-up of the nπ* population and to the emergence of coherences in the dynamics, to date unobserved. Nonlinear spectroscopy simulations call for the CNN in-plane bendings as the active modes in the sub-ps photoinduced coherent dynamics out of the ππ* state...
March 5, 2018: Journal of Physical Chemistry Letters
Heshu Fang, Xia Zhao, Yuan Lin, Song Yang, Jun Hu
Construction of stimuli-responsive materials using naturally occurring molecules as building blocks has received increasing attention in terms of bioavailability, biocompatibility, and biodegradability. In this research, a symmetrical azobenzene-functionalized natural glycyrrhizic acid (trans-GAG) was synthesized, which could form the stable supramolecular gels in DMSO/H2O and MeOH/H2O, respectively. On account of trans-cis isomerization, this gel exhibited a typical light-responsive behavior, thus leading to a reversible gel-sol transition accompanied with the variation in morphology and rheology...
March 5, 2018: Chemistry, An Asian Journal
Peiwen Zhao, Yuxiang Bu
We computationally design a series of azobenzene (AB)-bridged double radicalized nucleobases, a novel kind of diradical Janus-type nucleobases, and explore their spin coupling characteristics. Calculations prove that such diradical Janus-bases not only normally match with their complementary bases, but also exhibit well-defined diradical character with photo-convertible intramolecular magnetic couplings (antiferromagnetic vs. ferromagnetic). Combination of four radical nucleobases (rG, rA, rC, rT) and photoswitch AB can yield 10 diradical Janus-bases with different magnetic characteristics in which AB functions a bridge to mediate the spin coupling between two radical bases...
March 5, 2018: Journal of Computational Chemistry
Alexey V Bogdanov, Andrey Kh Vorobiev
The evolution of domain structure of two azobenzene-containing materials during irradiation with polarized light was monitored using polarized optical microscopy with additional λ-waveplate for discerning the domains oriented parallel and perpendicular to irradiating light polarization. It is shown that the process of photo-orientation consists in growth of perpendicularly oriented domains and diminishing of parallel domains via the movement of domain boundaries. These data confirm the mechanism of photo-orientation via domain structure rearrangement...
March 2, 2018: Journal of Physical Chemistry Letters
R F de Souza, E K Lenzi, R T de Souza, L R Evangelista, Q Li, R S Zola
Surface driven pattern formation is an intriguing phenomenon in the liquid crystal field. Owing to its ability to transmit torque, one can generate different patterns by propagating distortions on the optical wavelength scale in the sample from the surface. Here, we theoretically investigate (from the elasticity point of view) twist deformations induced by a rotating easy axis at one surface, by considering the anchoring energy and surface viscosity of nematic and chiral nematic samples. The model is solved analytically in the limit of strong anchoring and numerically for a low anchoring strength situation...
February 27, 2018: Soft Matter
Arun K Pal, Thomas J Duignan, Jochen Autschbach
Linear polarizabilities (α) and second hyperpolarizabilities (γ) of unsubstituted azobenzenes and 'push-pull' azobenzene derivatives are investigated using Kohn-Sham theory (KST) and coupled-cluster (CC) approaches. Various standard exchange-correlation functionals as well as a non-empirically 'tuned' long-range corrected (LC) functional with range-separated exchange are used in the KST calculations. When compared to correlated ab initio calculations and measurements, the tuned functional gives accurate low-energy excitation energies, especially for charge transfer (CT) transitions, and performs well for α...
February 27, 2018: Physical Chemistry Chemical Physics: PCCP
Christoph Nançoz, Giuseppe Licari, Joseph S Beckwith, Magnus Soederberg, Bogdan Dereka, Arnulf Rosspeintner, Oleksandr Yushchenko, Romain Letrun, Sabine Richert, Bernhard Lang, Eric Vauthey
The excited-state dynamics of the push-pull azobenzene Methyl Orange (MO) were investigated in several solvents and water/glycerol mixtures using a combination of ultrafast time-resolved fluorescence and transient absorption in both the UV-visible and the IR regions, as well as quantum chemical calculations. Optical excitation of MO in its trans form results in the population of the S2 ππ* state and is followed by internal conversion to the S1 nπ* state in ∼50 fs. The population of this state decays on the sub-picosecond timescale by both internal conversion to the trans ground state and isomerisation to the cis ground state...
February 27, 2018: Physical Chemistry Chemical Physics: PCCP
Kirill F Sheberstov, Hans-Martin Vieth, Herbert Zimmermann, Konstantin L Ivanov, Alexey S Kiryutin, Alexandra V Yurkovskaya
We provide a detailed evaluation of nuclear magnetic resonance (NMR) parameters of the cis - and trans -isomers of azobenzene (AB). For determining the NMR parameters, such as proton-proton and proton-nitrogen J -couplings and chemical shifts, we compared NMR spectra of three different isotopomers of AB: the doubly15 N labeled azobenzene,15 N,15 N'-AB, and two partially deuterated AB isotopomers with a single15 N atom. For the total lineshape analysis of NMR spectra, we used the recently developed ANATOLIA software package...
2018: Applied Magnetic Resonance
Tianxi Gao, Yajie Xue, Zan Zhang, Wenxiu Que
While single wavelength all-optical information encoding through optically induced orientation of azobenzene dyes is being extensively pursued, we propose multi-wavelength optical data processing and recording based on disperse red 1 (DR1) and 4-(4-hydroxybutyloxy) azobenzene doped organic-inorganic hybrid films to increase the density of recording data. By investigating the change of absorbance spectrum of the doped film under different irradiations, results indicate a laser pulses around 470 nm would be suitable as the probe beam...
February 19, 2018: Optics Express
Niels J Hauwert, Tamara A M Mocking, Daniel Da Costa Pereira, Albert J Kooistra, Lisa M Wijnen, Gerda Vreeker, Noortje W E Verweij, Bert H De Boer, Martine J Smit, Chris de Graaf, Henry F Vischer, Iwan J P De Esch, Maikel Wijtmans, Rob Leurs
Non-invasive methods to modulate G protein-coupled receptors (GPCRs) with temporal and spatial precision are in great demand. Photopharmacology uses photons to control in situ the biological properties of photoswitchable small-molecule ligands which bodes well for chemical biological precision approaches. Integrating the light-switchable configurational properties of an azobenzene into the ligand core, we developed a bi-directional antagonist toolbox for an archetypical family A GPCR, the histamine H3 receptor (H3R)...
February 22, 2018: Journal of the American Chemical Society
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